Since a laser light source has a longer life than a high pressure mercury lamp or the like, the optical system can be downsized, and the power consumption is also small, an illumination device and projection device using a laser light source are spreading.
The laser light source has a problem of speckle generation. However, Patent Literature 1 discloses a technique in which a traveling direction of a laser beam is periodically changed to temporally change the incident angle of a laser beam incident on each point of the illumination zone so as to make speckle less noticeable.